Method of manufacturing a component for use in a roller clutch assembly

ABSTRACT

A component for a roller clutch assembly includes a sleeve having a head part and a shank part, and the component is produced by first cropping a steel bar to produce a slug having a length to diameter ratio of not less than 0.75. The slug is then deformed into a substantially cylindrical billet having a diameter substantially equal to the diameter of the head part of the finished component. After heat treatment of the billet to remove work hardening, an axially extending, centrally disposed bore is formed in the billet and the billet is positioned in a die. Within the die, a punch is used to perform a first impact extrusion process on the billet so that metal flows in the direction of movement of the punch and produces a preform defining the shank part of the sleeve and having a head portion which tapers inwardly to towards said shank part. The preform is then heat treated to remove work hardening and a further punch is then used to perform a second impact extrusion process on the preform. In the second extrusion process, metal flows in the opposite direction to the direction of movement of the further punch and effects shaping of the preform so that the included angle of the tapering head portion of the preform is increased to produce the head part of the sleeve and thereby, the finished component.

United States Patent [191 Poulson et al.

[ METHOD OF MANUFACTURING A COMPONENT FOR USE IN A ROLLER CLUTCH ASSEMBLY [75] Inventors: Howard Poulson, Hampton Magna,

near Warwick; Ian Anthony Docket-ill, Solihull, both of England [73] Assignee: Joseph Lucas (Industries) Limited,

Birmingham, England 22 Filed: Mar. 1, 1972 21 Appl. No.: 230,563

[30] Foreign Application Priority Data [4 Oct. 16, 1973 Primary Examiner-Richard J. Herbst Attorney-John C. Holman et al.

[57] ABSTRACT A component for a roller clutch assembly includes a sleeve having a head part and a shank part, and the component is produced by first cropping a steel bar to produce a slug having a length to diameter ratio of not less than 0.75. The slug is then deformed into a substantially cylindrical billet having a diameter-substantially equal to the diameter of the head part of the finished component. After heat treatment of the billet to remove work hardening, an axially extending, centrally disposed bore is formed in the billet and the bi]- let is positioned in a die. Within the die, a punch is used to perform a first impact extrusion process on the billet so that metal flows in the direction of movement of the punch and produces a preform defining the shank part of the sleeve and having a head portion which tapers inwardly to towards said shank part. The preform is then heat treated to remove work hardening and a further punch is then used to perform a second impact extrusion process on the preform. In the second extrusion process, metal flows in the opposite direction to the direction of movement of the further punch and effects shaping of the preform so that the included angle of the tapering head portion of the preform is increased to produce the head part of the sleeve and thereby, the finished component.

13 Claims, 9 Drawing Figures PATENIEU um 15 I973 SHEET 10F 2 l lo FIG.I

FIG.3

METHOD OF MANUFACTURING A COMPONENT FOR USE IN A ROLLER CLUTCH ASSEMBLY This invention relates to a method of manufacturing a component for use in a roller clutch assembly, the component being of the kind including a sleeve having a head part and a shank part, the bore in the sleeve being stepped to define a wide portion within the head part and a narrow portion within the shank part, and the wall of said wide portion of the bore being shaped to define an internal cam surface in the head part.

A method according to the invention, includes the steps of:

a. cropping a steel bar to produce a slug having a length to diameter ratio of not less than 0.75,

b. deforming the slug into a substantially cylindrical billet having a diameter substantially equal to the diameter of the head part of the sleeve,

c. heat treating the billet to remove work hardening,

d. forming an axially extending, centrally disposed bore in the billet,

e. positioning the billet in a die and using a punch to perform a first impact extrusion process on the billet such that metal flows in the direction of movement of the punch and produces a preform defining the shank part of the sleeve and having a head portion which tapers inwardly to said shank part,

f. heat treating the preform to remove work hardening, and

g. using a further punch to perform a second impact extrusion process on the preform such that metal flows in the opposite direction to the direction of movement of the further punch and effects shaping of the preform so that the included angle of the tapering head portion of the preform is increased to produce the head part of the sleeve and thereby, the finished component.

Preferably, the minimum length to diameter ratio of the cropped slug is 1.

Preferably, the length of the slug is reduced by at least 30 percent during the deforming stage (b).

Preferably, the tapering head portion produced at step (e) defines an included angle of between 80 and 100 C.

Preferably, said included angle is increased to a value between 140 and 170 during the second impact extrusion step (g). i

Preferably, the second impact extrusion process is arranged to produce a plurality of angularly spaced ribs integral with the head part and extending inwardly from the wall of said wide portion of the bore.

Conveniently, step (d) is effected by a drilling operation.

Alternatively, step (d) is effected by an impact extrusion operation and then a piercing operation.

Conveniently, a tapered mandrel is positioned in the bore in the billet during the first extrusion process, the taper of the mandrel being such as to allow removal of the mandrel from the bore after formation of the preform without removal of the preform from the die.

In the accompanying drawings,

FIG. 1 is a sectional view of a component for use in a roller clutch assembly.

FIGS. 2 to 6 are sectional views illustrating five stages respectively during a method according to a first example of the invention of producing the component shown in FIG. 1,

FIGS. 7 and 8 are sectional views illustrating two stages respectively during a method, according to a second example of the invention, of producingthe component shown in FIG. 1, and

FIG. 9 is a sectional view illustrating one stage during a method according to a modification of the second example.

Referring to FIG. 1 it is desired to manufacture a component for use in a roller clutch assembly, the component being of the kind including a sleeve 9 having a head part 9a and a shank part 9b joined to the head part by a tapering portion 9c. The bore 10 in the sleeve is stepped to define a wide portion 10a in the head part 9a and a narrow portion 10b in the shank part 9b, the wall of the wide portion 10a of the bore 10 defining an internal cam surface (not shown) in the head part 9a.

As shown in FIGS. 2 to 6, in a first example of the invention the component was manufactured from a bright drawn steel bar 11, the steel used in the bar 11 having the following composition by weight: carbon 0.21 percent, manganese 1.24 percent, silicon 0.3 percent, sulphur 0.033 percent, phosphorus 0.06 percent, nickel 0.13 percent, chromium 0.23 percent, molybdenum 0.15 percentand copper 0.15 percent, the remainder being iron. The bar 11 was cropped by means of a tool 12 (FIG. 2) so as to produce a slug 13, the feeding of the bar 11 into the cropping tool 12 being controlled by means of a fixed stop (not shown) so that the cropping operation produced a slug 13 of constant weight, the weight of the slug formed being determined by the volume of the slug necessary to produce a finished component of the desired dimensions. In the particular example the tool 12 was arranged to produce a slug 13 having a weight of 545 gm, the length of the slug being 43.4 mm and the diameter of the slug 44.45 mm. As shown in FIG. 3, the slug 13 was then formed by a press 14 into a billet 15 shaped so that the periphery of the billet 15 defined a substantially cylindrical surface with the diameter of the billet being substantially equal to the required head diameter of the finished component, which in the particular example was 58.9mm. Deforming of the slug 13 also reduced the length of the slug to a value of 26.4mm for the billet 15. i

To effect the deforming operation a load of 350 tons was applied to the punches of the press 14 and after formation of the billet 15, a spheriodising heat treatment process was carried out by heating the billet for 4 hours at 680 C. Lubrication was then applied to the billet by a standard phosphating and soaping application, whereafter an axially extending, centrally disposed bore 16 having a diameter of 20.5 mm, that is approximately 0.5mm larger than that required in the shank part 9b of the required component, was formed in the billet 15 by means of a drill 17 (FIG. 4) and the drilled billet was positioned in an extrusion die 18. Preferably, to facilitate location of the billet 15 in the die 18, the deformation of the slug 13 by the press 14 was arranged to produce an annular ring (not shown) on the periphery of the billet 15, the width of the ring being controlled so as to prevent creation of large stresses in the tools during subsequent operations.

With the billet 15 in position in the die 18 a first impact extrusion process was carried out on the billet 15 by applying a pressure of 288 tons to the billet 15 through a first extrusion punch 19. During the extrusion process metal flowed from the billet 15 in the direction of movement of the punch 19, the die 18 being arranged so that the extrusion produced a preform 21 having a shank portion 21b, defining the shank part 9b of the required component, and a head portion 21a of diameter equal to the diameter of the head part 9a of the required component. The extrusion process also produced a tapering portion 21c joining the head portion 21a and the shank portion 21b, the taper of the portion 21c being such that the included angle of the taper was 80. Also, a mandrel 22 extending through the punch 19 was received in the bore 16 in the billet during the extrusion process so that the extrusion produced a bore in the preform 21, which was of course required since the finished component is in the form of a sleeve 9 having a bore 10 extending therethrough. Further, the mandrel 22 was provided with a slight taper so as to allow the mandrel to be removed from the preform after extrusion without the preform being removed from the die 18.

When the extrusion of the preform 21 was complete and the punch 19 and the mandrel 22 had been removed from the die 18, the preform 21 was ejected from the die by means of an ejector punch 23 and subsequently it was heat treated at 680 C for 4 hours. The preform 21 was then lubricated by a standard phosphating and soaping treatment and subsequently was positioned in a further die 24 (FIG. 6) and a second impact extrusion process was carried out on the preform. In this case, extrusion was effected by applying a load of 242 tons through a second extrusion punch 25 to the free end of the head portion 21a of the preform. A further mandrel 26 was positioned in the bore in the preform 21 and the free end of the shank portion 21b of the preform was held against movement by a stationary punch 27, whereby application of pressure to the preform 21 through the punch 26 caused flow of metal in the opposite direction to the direction of movement of the punch. The arrangement of the die 24 was such that the flow of metal during this backward extrusion process further shaped the preform 21 to define the head part 9a of the sleeve 9 and thereby produce the required component. During this second extrusion process the tapered portion 21c of the preform 21 was reshaped to produce the tapering portion 90 of the component 9, the included angle of the taper being increased to value of 140 for the portion 9c.

It is to be appreciated that the punch 25 is arranged so that the backward extrusion process produces the required internal cam surface in the head part 9a. Furthermore the punch 25 is shaped so that the backward extrusion process produces a plurality of integral, angularly spaced ribs 28 which extend inwardly from the wall of the wide portion 10a of the bore 10. In a roller clutch assembly, each of the ribs 28 defines an abutment against which a spring is flexed so as to urge a roller into engagement with the cam surface on the wall of the wide portion 10a of the bore 10.

Further it is to be appreciated that since the mandrel 22 is tapered so as to facilitate removal of the mandrel from the preform 21 after the first extrusion process, the bore in the preform 21 will also be tapered. However, by arranging that the further mandrel 26 is of constant thickness along its length, then the second extrusion process will remove the taper from the bore in the preform 21 so that the bore 10b in the shank part 9b of the sleeve 9 will be of the required constant diameter.

Referring now to FIGS. 7 and 8, in a second example of the invention, the component 9 was manufactured from a centreless, turned steel bar having the same chemical composition as the bar 11 of the first example. The bar was cropped as before to produce a slug, the weight of the slug now being between 480 and 500 grams and the diameter and length of the slug being 1.63 inch and 1.88 inch respectively. The deforming operation was carried out in the same way as shown in FIG. 3 for the first example, with a load of 350 tons being applied to the punches of the press 14. The billet produced by the deforming operation had a diameter of 2.288 inch and a length of 0.975 inch. The billet was then spheroidised by heating for 4 hours at 680 C, whereafter lubrication was applied to the billet by a standard phosphating and soaping application.

An axially extending, centrally disposed bore was then formed in the lubricated billet but now, instead of using a drilling operation, the hole was produced by a combination of an extrusion operation (FIG. 7) and a piercing operation (FIG. 8). Thus, the lubricated billet, shown at 31 in FIGS. 7 and 8, was first positioned in a die 32 and, using a two part punch 33, an impact extrusion operation was performed on the billet 31 to produce a blind bore 30 in the billet. The tip 34 of the punch 33 was formed of tungsten carbide sold by Wickman Wimet as grade C.T., which contained 9 percent by weight of cobalt, had a grain size of 3 microns, and a density of 14.65 gm/c.c. A tool steel punch holder 35 supported the carbide punch tip 34 and a high speed steel backing piece 36 which formed the other part of the two-part punch 33. In the particular example, a load of 73 tons was applied to the punch 33 to effect the bore extrusion which produced a cylindrical, blind bore in the billet 31 of diameter 0.803 inch, the length and external diameter of the billet, after extrusion, being 1.200 inch and 2.298 inch respectively. Considerable stresses were experienced by the tip 34 during the bore extrusion operation and so, as can be seen in FIG. 6, the tip 34 was shaped to minimise these stresses. Formation of the bore in the billet 31 was then completed by piercing the blind bore 30 using the tool shown at 37 with an applied load of 20 tons.

The pierced billet was then heat treated to recrystalise the work hardened ferrite grains in the steel by passing the billet through a conveyor furnace at a speed of 2.5 inches per minute with the furnace temperature being held at 710720 C and the furnace being supplied with exothermic gas. After recrystalisation, the billet was lubricated using a standard phosphating and soaping treatment and was then extruded, in the manner of the first example, to produce a preform 21 (FIG. 5). However, in this case, a load of 290 tons was applied to the punch 19 and the die 18 was arranged so that the taper of the portion 21c of the preform defined an included angle of After heat treatment at 680 C for 4 hours, the preform 21 was subjected to a backward extrusion operation, in a manner shown in FIG. 6, by applying a load of 262 tons to the punch 25. The component 9 thus produced was substantially identical with the component produced by the first example.

In a modification of the second example, as shown in FIG. 9, it was desired to produce a roller clutch component, similar to that shown at 9 in FIG. 1. However, the component of this modification was required to define, between its head portion and its shank portion, a tapering portion such that the included angle of the taper was 170. The method of producing the component was substantially the same as that of the second example. Thus, a centreless, turned steel bar was first cropped to produce a slug of weight between 215 and 220 grams, of diameter 1.260 inch and of length 1.240 inch. The slug was then deformed into a substantially cylindrical billet of diameter 1.832 inch and axial length 0.676 inch by applying a load of 260 tons to the slug by means of the punches of a press similar to that shown in P16. 3. Then, following lubrication of the billet, an axially extending, centrally disposed bore was produced in the billet by an impact extrusion operation and then a piercing operation. The impact extrusion operation, which is illustrated in FlG. 9, followed closely the corresponding operation in the previous example, although in this case it was required to produce a tapering bore in the billet so that the punch tip, shown at 41, was tapered also. As before, the punch tip 41 was formed of grade C.T. tungsten carbide and was sup ported, together with a high speed steel backing piece 42, in a tool steel punch holder 43. In this modification, extrusion was effected by applying a load of 48 tons to the punch tip 41, the blind bore thus produced in the billet being pierced in the same way as the previous example. The resultant pierced billet had an external diameter OH .839 inch, and an axial length of 0.800 inch, and had a tapering bore of mean diameter 0.662 inch and an angle of taper of 2 28. Subsequent processing of the billet proceeded in the same way as the previous example, although now the first, forward extrusion operation was effected by applying a load of 284 tons to the punch 19 with the tapered mandrel 22 being received in the tapered bore in the billet. The second, backward extrusion operation was effected by applying a load of 145 tons to the punch 25.

Each of the components produced in the examples described above is particularly designed for use as a roller clutch sleeve for a starter motor. It will therefore be appreciated that further processing of the finished component is required to produce helical grooves in the wall of the narrow portion b of the bore 10 for engagement with complementary splines on the rotor shaft of the starter motor.

We claim:

1. A method of manufacturing a component of the kind specified for use in a roller clutch assembly, the method including the steps of:

a. cropping a steel bar to produce a slug having a length to diameter ratio of not less than 0.75,

b. deforming the slug into a substantially cylindrical billet having a diameter substantially equal to the diameter of the head part of the sleeve,

c. heat treating the billet to remove work hardening,

d. forming an axially extending, centrally disposed bore in the billet,

e. positioning the billet in a die and using a punch to perform a first impact extrusion process on the billet such that metal flows in the direction of movement of the punch and produces a preform defining the shank part of the sleeve and having a head portion which tapers inwardly to said shank part,

f. heat treating the preform to remove work hardening, and

g. using a further punch to perform a second impact extrusion process on the preform such that metal flows in the opposite direction to the direction of movement of the further punch and effects shaping of the preform so that the included angle of the tapering head portion of the preform is increased to produce the head part of the sleeve and thereby, the finished component.

2. A method as claimed in claim 1 wherein the heat treatment step (c) is a spheroidising operation.

3. A method as claimed in claim 1 wherein the heat treatment step (f) is a spheroidising operation.

4. A method as claimed in claim 1 wherein the length to diameter ratio of the cropped slug is unity.

5. A method as claimed in claim 1 wherein the length of the slug is reduced by at least 30 percent during the deforming stage (b).

6. A method as claimed in claim 1 wherein the tapering head portion produced at step (e) defines an included angle of between and C.

7. A method as claimed in claim 1 wherein said included angle is increased to a value between and during the second impact extrusion step (g).

8. A method as claimed in claim 1 wherein the second impact extrusion process is arranged to produce a plurality of angularly spaced ribs integral with the head part and extending inwardly from the wall of said wide portion of the bore.

9. A method as claimed in claim 1 wherein step (d) is effected by-a drilling operation.

10. A method as claimed in claim I wherein step (d) is effected by an impact extrusion operation and then a piercing operation.

11. A method as claimed in claim 10 wherein following the piercing operation, the billet is heat treated to remove work hardening.

12. A method as claimed in claim 11, wherein the heat treatment is a recrystallisation process.

13. A method as claimed in claim 1 wherein a tapered mandrel is positioned in the bore in the billet during the first extrusion process, the taper of the mandrel being such as to allow removal of the mandrel from the bore after formation of the preform without removal of the preform from the die. 

1. A method of manufacturing a component of the kind specified for use in a roller clutch assembly, the method including the steps of: a. cropping a steel bar to produce a slug having a length to diameter ratio of not less than 0.75, b. deforming the slug into a substantially cylindrical billet having a diameter substantially equal to the diameter of the head part of the sleeve, c. heat treating the billet to remove work hardening, d. forming an axially extending, centrally disposed bore in the billet, e. positioning the billet in a die and using a punch to perform a first impact extrusion process on the billet such that metal flows in the direction of movement of the punch and produces a preform defining the shank part of the sleeve and having a head portion which tapers inwardly to said shank part, f. heat treating the preform to remove work hardening, and g. using a further punch to perform a second impact extrusion process on the preform such that metal flows in the opposite direction to the direction of movement of the further punch and effects shaping of the preform so that the included angle of the tapering head portion of the preform is increased to produce the head part of the sleeve and thereby, the finished component.
 2. A method as claimed in claim 1 wherein the heat treatment step (c) is a spheroidising operation.
 3. A method as claimed in claim 1 wherein the heat treatment step (f) is a spheroidising operation.
 4. A method as claimed in claim 1 wherein the length to diameter ratio of the cropped slug is unity.
 5. A method as claimed in claim 1 wherein the length of the slug is reduced by at least 30 percent during the deforming stage (b).
 6. A method as claimed in claim 1 wherein the tapering head portion produced at step (e) defines an included angle of between 80* and 100* C.
 7. A method as claimed in claim 1 wherein said included angle is increased to a value between 140* and 170* during the second impact extrusion step (g).
 8. A method as claimed in claim 1 wherein the second impact extrusion process is arranged to produce a plurality of angularly spaced ribs integral with the head part and extending inwardly from the wall of said wide portion of the bore.
 9. A method as claimed in claim 1 wherein step (d) is effected by a drilling operation.
 10. A method as claimed in claim 1 wherein step (d) is effected by an impact extrusion operation and then a piercing operation.
 11. A method as claimed in claim 10 wherein following the piercing operation, the billet is heat treated to remove work hardening.
 12. A method as claimed in claim 11, wherein the heat treatment is a recrystallisation process.
 13. A method as claimed in claim 1 wherein a tapered mandrel is positioned in the bore in the billet during the first extrusion process, the taper of the mandrel being such as to allow removal of the mandrel from the bore after formation of the preform without removal of the preform from the die. 